The objectives of this project are to study factors (e.g., type of dietary fat, exercise, species) affecting cholesterol absorption, tissue distribution, and biosynthesis in animals, principally but not exclusively ruminants. Methodology for studying cholesterol absorption currently is being evaluated. During the coming year we propose to refine our methods for measuring absorption and to study the effects of dietary variables, with particular attention being given to type of fat, e.g., saturated (tallow) and unsaturated (soybean oil). We propose also to extend our observations on the effect of exercise on cholesterol absorption, tissue distribution and atherogenesis. Our work will be conducted principally with the goat (which our data have established as an excellent model animal because of the similarity of atherosclerotic lesions to those in man) and the calf, but comparative studies will be conducted with rats and rabbits.